The present invention relates to the removal of moisture from air, especially for use in mine air-cleaning systems.
In many working environments substantial quantities of dust are present which, if not removed, are considered hazardous to personnel. In a mine environment, for example, in which operator-controlled continuous miner machines are utilized, it is important that large amounts of dust be removed from the air so that respirable dust levels do not exceed certain limits.
Air-cleaning systems have heretofore been utilized which employ a liquid spray (preferably water) to clean dust from the air. In such a system air is sucked-in through one or more inlet ducts toward the front of the miner by means of a fan. The fan is located downstream and receives air flow(s) from the inlet duct(s). Mounted preferably upstream of the fan area a "scrubber" and a "demister". Dust-laden air first passes through the scrubber while a high pressure water spray is introduced into the air flow to precipitate and wash-out some of the dust and other solids. The remaining solids become entrained within water droplets and continue-on within the air flow. Thereafter, such entrained dust and water-laden air flow passes through the demister which typically comprises an air inlet, an air outlet, a sump and a maze of "profiles" or louvers which cause "moisture" (i.e., pure water or water with contained solids) in the air to be separate-out and gravitate toward the sump located below the louvers. The clean, relatively dry air from the demister is then exhausted through the fan and usually thereafter through a widened exhaust duct.
Although air-cleaning systems of the above-identified type have performed satisfactorily in the past, certain shortcomings persist, especially regarding the size and performance of the demister apparatus. As regards size, the demister units currently available are generally of such height that they may be conveniently located on the miner only in certain areas where height is available. One such location is to the operator's left on the opposite side of the main discharge conveyor. With the demister in that location, however, the operator's vision to the left is impaired, thereby hampering efforts in making left-hand turns. In addition, such location of the demister has resulted in the fan motor being positioned so near to the operator that a substantial amount of noise therefrom can be discerned by the operator. Since the permissible duration of an operator's working shift may be influenced by the dosage of noise to which he is subjected, a more frequent replacement of operators may be necessary.
Concerning performance of the demister, a conventional demister is characterized by a maximum level of air inlet velocity which cannot be exceeded if acceptable performance is to be maintained. This, in effect, limits the rate of air flow which can be established through the demister, and thus limits the rate of demisting which can be attained. Other problems include the re-entrainment of moisture into the air flow due to the particular air flow patterns established in the demister.
It is, therefore, an object of the present invention to minimize or obviate shortcomings of the above-mentioned type.
It is another object of the invention to provide a novel demister apparatus and a novel demisting method.
It is a further object of the invention to enable the size, especially the height, of a demister to be reduced.
It is an additional object of the invention to enable the demister to be positioned further from the operator's station on a miner.
It is still another object of the invention to enable the efficiency of a demister to be increased.
It is still another object of the present invention to provide a novel air cleaning apparatus which can be retrofit to existing mining machines.